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Schwietzke s 20150708_1730_upmc_jussieu_-_amphi_24

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Schwietzke s 20150708_1730_upmc_jussieu_-_amphi_24

  1. 1. 2 Stefan Schwietzke1,2, Owen Sherwood2, Pieter P. Tans1, Sylvia Englund Michel2, Giuseppe Etiope3, Artur Ionescu4, John B. Miller1,2, Edward J. Dlugokencky1, Lori M. P. Bruhwiler1, Victoria A. Arling2 1NOAA/GMD Boulder, 2Univ. of Colorado Boulder, 3INGV Italy, 4Babes-Bolyai Univ. Romania Funding: National Research Council RAP, CIRES IRP Global methane budget and natural gas leakage based on long-term δ13CH4 measurements and updated isotopic source signatures
  2. 2. 2 2 0% 20% 40% 60% 80% 100% Uncertainties in attribution of global CH4 sources Photo sources: Wikimedia • Based on atmospheric measurements of CH4, δ13CH4, and/or C2H6 Mikaloff et al. 2004 (illustrative) Bousquet et al. 2006 (illustrative)
  3. 3. 2 3 -48 -47.5 -47 -46.5 -46 1985 1989 1993 1997 2001 2005 2009 2013 Globalannualmeanδ13C(‰) Year Confidence in observational and δ13C signature constraints 0 100 200 300 400 500 600 1550 1600 1650 1700 1750 1800 1850 1985 1989 1993 1997 2001 2005 2009 2013 GlobalCH4fluxes(Tg/year) GlobalannualmeanCH4(ppb) Year Global mean CH4 mixing ratio and flux Global δ13CH4 observations δ13CH4 source signatures CH4 lifetime 9.4 ± 0.3 years (9.1 ± 0.9 years) Uncertainties ± 0.1‰ incl. site-selection bias NOAA Global GHG Reference Network • Only few published global estimates • Uncertainties not well characterized • New analysis in this work
  4. 4. 2 4 Mass balance of 3 CH4 source categories -53‰ -47‰ (Obs.) “Other” Wetlands, ruminants, rice, landfills, termites Isotopic fractionation Biomass burning Oil/gas, coal • Global δ13CH4 signature database for the different CH4 sources • Monte Carlo simulation - Propagation of all uncertainties in source allocation Total CH4 isotopically more depleted isotopically more enriched
  5. 5. 2 5 Global δ13CH4 source signature literature database developm. (1) Sample size Sample percentage of global production Oil/Ga s 3,085 40% Coal 660 58% Oil/Gas Coal Oil/Gas, Coal Quay et al. 1999 Miller 2005 Fossil fuels, this work GLOREG (Global Reservoir Gas data-set)
  6. 6. 2 6 Sample size Sample regions Biomass burning 11 Boreal, temperate, tropical Other* 70 5 continents, 13 countries * Wetlands, ruminants, rice, landfills, termites Quay et al. 1999 Miller 2005 Biomass burning This work Quay et al. 1999 Miller 2005 This work Other Global δ13CH4 source signature literature database developm. (2)
  7. 7. 2 7 0 50 100 150 200 250 300 350 400 450 1985 1989 1993 1997 2001 2005 2009 2013 GlobalCH4emissions(Tg/yr) Year Other (Wetlands, Ruminants, Rice, Landfills, Termites) Oil/Gas, Coal Results: fossil fuel CH4 higher than most previous estimates Literature range of Oil/Gas, Coal (incl. geolog. seeps)
  8. 8. 2 8 0 50 100 150 200 250 300 350 400 450 1985 1989 1993 1997 2001 2005 2009 2013 GlobalCH4emissions(Tg/yr) Year Literature range of Oil/Gas, Coal –45‰ (this study) Other Oil/Gas, Coal –40‰ (Quay et al. 1999, Miller 2005) Strong influence of oil/gas, coal δ13CH4 signature on emissions
  9. 9. 2 9 0 50 100 150 200 250 δ Other τ ε BB emissions δ BB δ Fossil fuels Soil sink Global FF emissions in 2011 (Tg CH4/yr) FF CH4 emissions sensitivity analysis C.I. (10, 90th Percentiles) -59, -63 ‰ 10.0, 8.2 yr -7.1, -5.5 ‰ 55, 32 Tg/yr -20, -32 ‰ -44.7, -46.5 ‰ 34, 30 Tg/yr δ Other τ ε BB emissions δ BB δ Fossil fuels Soil sink Parameters Median * *
  10. 10. 2 10 ALT Inter-hemispheric gradient test: preliminary TM5 results Measurement sites BRW CBA UUM AZR TAP WIS KEY MLO RPB CHR SEY ASC EIC CRZ SPO (annual mean 2001)
  11. 11. 2 11 Paleo test – same parameter distributions as 1984-2013 • Geological seeps: 15–100 Tg/yr • Pre-industrial δ13CH4 (ice core) measurements and biomass burning emissions from Ferretti et al. 2005 0 50 100 150 200 250 300 350 50 200 350 500 650 800 950 1100 1250 1400 1550 1700 1850 2000 GlobalCH4emissions(Tg/yr) Year Other (Wetlands, Ruminants, Rice, Landfills, Termites) Geologic seeps Includes fossil fuel industries
  12. 12. 2 12 -2 0 2 4 6 8 10 12 14 1985 1989 1993 1997 2001 2005 2009 2013 GlobalaverageFER(%) Year Natural gas fugitive emissions rate (% of production) decreasing • Median natural gas fugitive emissions rate 2.5% (based on δ13CH4) during most recent 5 years (geological seepage accounted for) • Bottom-up coal and oil CH4 emissions, and natural gas composition from Schwietzke et al. 2014
  13. 13. 2 13 Conclusions • Global fossil fuel CH4 emissions – comparison with previous studies - Higher than CH4 inversion studies (~150 Tg/yr prelim.) - Largely due to lighter fossil fuel δ13CH4 source signature and updates in atmospheric transport (TM5) - Consistent with ice core data, which confirms bottom-up estimates of global geological seep (≥15 Tg/yr) • Natural gas fugitive emissions rate declining since the mid-1980s, with current best estimate of 2.5%

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